This application is related to U.S. Pat. Nos. 5,165,163; 5,186,239; and 5,257,454 all assigned to the assignee of the present application.
1. Field of the Invention
The present invention relates generally to a heat exchanger for an automotive vehicle. More particularly, the present invention relates to an automotive heat exchanger core having a thermal stress-relieving zone therein.
2. Disclosure Information
Typical automotive heat exchangers, such as radiators, include a plurality of thin-walled tubes interleaved with corrugated fins enclosed in a core frame. The fins are rigidly attached to the tubes as well as to a pair of frame side supports while the tubes are joined to a pair of headers. The frame side supports are attached also to the headers. As is well known in the art, coolant passes from one header through the tubing to the other header. As the temperature of the coolant passing through the heat exchanger core increases, the core expands. The frame side supports, however, are not in direct heat contact with the liquid and, as such, do not heat at a proportional rate to the heating of the tubing. As a result of the expansion and contraction of the tubing, the side supports induce thermal stress in the tube-to-header joints during the thermal cycling of the heat exchanger, often leading to durability problems such as cracking or leaking of the tubes.
To overcome this thermal cycling problem and to increase the durability of the heat exchanger core, it is known in the art to relieve the thermally-induced stress by providing an oblong-shaped slot in one of the side supports and subsequently fracturing the side support at the slot. U.S. Pat. Nos. 5,165,163; 5,186,239; and 5,257,454, all assigned to the assignee of the present application, disclose a method and apparatus for fracturing a side support of a heat exchanger through the use of an oblong-shaped slot. As taught in these patents, a shearing tool applies a shearing force against the flanges of the side support proximate the slot to fracture the side support and provide a thermal stress relieving zone. However, in this method, the flanges of the side supports are fractured toward each other, resulting in a pair of tabs being disposed within an interior channel of the side support.
Typically, an elastomeric sealing strip or member is placed within the channel of the side support to provide sound deadening and insulation. This strip is placed within the side support channel after the side support has been fractured. It has been found that the tabs resulting from fracturing the side supports by the above-described method often interfere with the placement of the elastomeric strip into the channel of the side support and that scrap often results since the elastomeric strips are damaged during insertion. Therefore, it would be advantageous to provide a heat exchanger and method of manufacturing a heat exchanger which eliminates the tabs produced during the fracturing process.
It is an object of the present invention to provide a heat exchanger having a core including a side support defining a thermal stress-relieving zone therein which maintains core rigidity during assembly and brazing of the heat exchanger core while offering an efficient and simple means to relieve thermally-induced stress experienced by the heat exchanger.
It is further an object of the present invention to provide a thermal stress-relieving zone which does not interfere with or damage the elastomeric strips placed within the side support.